SKF Baker AWA-IV 12 HO, Руководство пользователя

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The PI test is performed on motor of 100 Hp or greater. The PI minimum alarm should be
set a 2.0 for class B, F, and H insulation, and 1.5 for class A insulation.
It is important to note that PI should not be used as the basis for any motor acceptance
criteria. It should be used as a trending and diagnostic tool, along with other test results
include the PI curve generated by the tester.
The PI test can be used to identify the following possible motor issues:
• Slot liner insulation or enamel wire insulation could be burned or damaged.
• The motor might be full of dirt, carbon dust, water, or other contaminants.
• Motor windings shorted to ground.
• Poor cable insulation.
The DA is essentially the same as PI, but shorter in duration (10 min vs 3 min). The first
minute for both tests is the megohm test.
HiPot test
A HiPot test is performed using a test voltage that is substantially higher than the MegOhm
test; however, it should be based on the motor’s operating voltage and the appropriate
standards/company guidelines.
During HiPot testing, look for unusually high leakage currents, a leakage current that does
not stay constant, or a leakage current that intermittently jumps up and down.
Breakdowns or high leakage currents are indications of damaged ground wall insulation.
Inspect the motor’s slot liner, wedges, conductors between the junction box and the coils, and
so on.
No further testing is necessary until the reason for an unacceptable HiPot reading is found
and corrected.
Step Voltage test
The Step Voltage test is used for predictive maintenance and field-testing. This DC test is
performed at a voltage level of what the motor typically experiences during starting and
stopping. The test voltages are governed by IEEE or other industry-accepted standards
organizations such as NEMA, EASA, and IEC.
The DC voltage is applied to all three phases of the winding, raised slowly to a predetermined
step level, and held for a predetermined time period. This is continued until the target test
voltage is reached.
Because the test is most stable at the end of each step, data is logged at that time. If at that
time the leakage current (IµA) doubles, insulation weakness is indicated and the test should
be stopped. If the leakage current (IµA) increases consistently less than double, the motor
insulation is likely in good condition.
Surge test
A Surge test is performed on each phase of the motor, using a test voltage based on the
motor’s operating voltage and the appropriate standards/company guidelines.
Look for a jump to the left of the surge waveform pattern; this is the signature of a turn-to-
turn short. If a jump is observed, inspect the motor. Look for damaged insulation between
adjacent conductors.
The insulation might be hard to see, so you might have to disassemble the motor to find the
problem. If you do not observe a jump in the wave patterns, the likelihood of motor failure
due to turn insulation failure is greatly reduced.
PUB CM/I4 71-015 EN V13.2 Static Motor Analyzer—Baker AWA-IV User Manual 79
Test procedures